Tsunami Warning System Research Articles

Automatic real time parameter determination of tsunami earthquakes in the Far East of Russia: Algorithms and software

A system of algorithms and software modules is described for automatic real time determination of epicenters and magnitudes of potential tsunami earthquakes. Modules are compiled into a single software system called Tsunami Source Quick Location (SS TSQL). The TSQL complex was successfully tested on dozens of real digital recordings. Currently, the TSQL complex is continuously operated in a test mode within the first phase of the seismic subsystem of the Tsunami Warning System (SS TWS) in the Far East of Russia.

Japan's tsunami warning system retreats

Japan's tsunami warning system retreats

Retrospective short-term forecast of the 1996 Andreanov (Aleutian Islands) tsunami

A brief review of the problem of short-term (operative) tsunami forecasting is presented. A method of short-term tsunami forecasting based on the sea level data at remote points is described. The forecast is based only on the seismological information about the coordinates of the earthquake’s epicenter. The application of this method for a retrospective forecast of the 1996 Andreanov tsunami demonstrates a satisfactory coincidence with the predicted and observed tsunami waveforms. The results are compared with the modeling prediction of the same event by other authors. The suggested method of the operative tsunami forecast can serve a basis for the development of a unique programming complex for operative forecasting and can be realized within regional and local tsunami warning services. The method can be used in tsunami warning systems at the stage of their development.

Contingency planning for natural disasters

Contingency planning for natural disasters

Anatomy of Historical Tsunamis: Lessons Learned for Tsunami Warning

Tsunamis are high-impact disasters that can cause death and destruction locally within a few minutes of their occurrence and across oceans hours, even up to a day, afterward. Efforts to establish tsunami warning systems to protect life and property began in the Pacific after the 1946 Aleutian Islands tsunami caused casualties in Hawaii. Seismic and sea level data were used by a central control center to evaluate tsunamigenic potential and then issue alerts and warnings. The ensuing events of 1952, 1957, and 1960 tested the new system, which continued to expand and evolve from a United States system to an international system in 1965. The Tsunami Warning System in the Pacific (ITSU) steadily improved through the decades as more stations became available in real and near-real time through better communications technology and greater bandwidth. New analysis techniques, coupled with more data of higher quality, resulted in better detection, greater solution accuracy, and more reliable warnings, but limitations still exist in constraining the source and in accurately predicting propagation of the wave from source to shore. Tsunami event data collected over the last two decades through international tsunami science surveys have led to more realistic models for source generation and inundation, and within the warning centers, real-time tsunami wave forecasting will become a reality in the near future. The tsunami warning system is an international cooperative effort amongst countries supported by global and national monitoring networks and dedicated tsunami warning centers; the research community has contributed to the system by advancing and improving its analysis tools. Lessons learned from the earliest tsunamis provided the backbone for the present system, but despite 45 years of experience, the 2004 Indian Ocean tsunami reminded us that tsunamis strike and kill everywhere, not just in the Pacific. Today, a global intergovernmental tsunami warning system is coordinated under the United Nations. This paper reviews historical tsunamis, their warning activities, and their sea level records to highlight lessons learned with the focus on how these insights have helped to drive further development of tsunami warning systems and their tsunami warning centers. While the international systems do well for teletsunamis, faster detection, more accurate evaluations, and widespread timely alerts are still the goals, and challenges still remain to achieving early warning against the more frequent and destructive local tsunamis.

Verification of Disaster Management Information on the 2004 Indian Ocean Tsunami Using Virtual Tsunami Warning System

There is still no tsunami warning systemprotecting the shores of the Indian Ocean, but imagine that a tsunami warning system had been in operation at the time of the 2004 Indian Ocean Tsunami. What disaster management information would have been issued for this tsunami ? This paper first proposes four tsunamimodels based on the earthquake information issued by different institutions. Next, setting these tsunami models as the initial condition, tsunami simulations are conducted to find the height of the tsunami striking the coastline around the Indian Ocean. As a result, it is indicated that because the tsunami model immediately after occurrence of the 2004 Sumatra Earthquake and the Indian Ocean tsunami calculated from this model are underestimated, appropriate tsunami warnings would most probably not have been issued before the 2004 tsunami struck land.

Atmospheric boundary waves excited by the tsunami generation related to the 2011 great Tohoku-Oki earthquake

[1] Atmospheric pressure changes caused by the 2011 Off the Pacific Coast of Tohoku, Japan earthquake (Mw = 9.0) are investigated. Sensitive microbarographs in and around Japan recorded unequivocal signals associated with the tsunami. We identify them as atmospheric boundary waves excited by the uplift and subsidence of the ocean surface, on the basis of the waveform characteristics as well as similarity with the data from ocean-bottom pressure gauges. Potential usefulness of an observation network of atmospheric pressure is discussed regarding the improvement of the tsunami warning system.

Relationship of Tsunami Intensity to Source Earthquake Magnitude as Retrieved from Historical Data

Operational prediction of near-field tsunamis in all existing Tsunami Warning Systems (TWSs) is based on fast determination of the position and size of submarine earthquakes. Exceedance of earthquake magnitude above some established threshold value, which can vary over different tsunamigenic zones, results in issuing a warning signal. Usually, a warning message has several (from 2 to 5) grades reflecting the degree of tsunami danger and sometimes contains expected wave heights at the coast. Current operational methodology is based on two main assumptions: (1) submarine earthquakes above some threshold magnitude can generate dangerous tsunamis and (2) the height of a resultant tsunami is, in general, proportional to the earthquake magnitude. While both assumptions are physically reasonable and generally correct, statistics of issued warnings are far from being satisfactory. For the last 55 years, up to 75% of warnings for regional tsunamis have turned out to be false, while each TWS has had at least a few cases of missing dangerous tsunamis. This paper presents the results of investigating the actual dependence of tsunami intensity on earthquake magnitude as it can be retrieved from historical observations and discusses the degree of correspondence of the above assumptions to real observations. Tsunami intensity, based on the Soloviev-Imamura scale is used as a measure of tsunami “size”. Its correlation with the Ms and Mw magnitudes is investigated based on historical data available for the instrumental period of observations (from 1900 to present).

GPS water level measurements for Indonesia's Tsunami Early Warning System

Abstract. On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements. The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS) (Rudloff et al., 2009) combines GPS technology and ocean bottom pressure (OBP) measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information. The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

GPS-controlled tide gauges in Indonesia – a German contribution to Indonesia's Tsunami Early Warning System

Abstract. Coastal tide gauges do not only play a central role in the study of climate-related sea level changes but also in tsunami warning systems. Over the past five years, ten GPS-controlled tide gauge systems have been installed by the German Research Centre for Geosciences (GFZ) in Indonesia to assist the development of the Indonesian Tsunami Early Warning System (InaTEWS). These stations are mainly installed at the Indonesian coastline facing the Indian Ocean. The tide gauge systems deliver information about the instantaneous sea level, vertical control information through GPS, and meteorological observations. A tidal analysis at the station's computer allows the detection of rapid changes in the local sea level ("sea level events"/SLE), thus indicating, for example, the arrival time of tsunamis. The technical implementation, communication issues, the operation and the sea level event detection algorithm, and some results from recent earthquakes and tsunamis are described in this paper.

Forced commutation controlled series capacitor (FCSC) circuit applied to stand-alone wave energy conversion buoys

Stand-alone buoys are used as navigation aids and for scientific marine research, including the measurement of seismographic movements of the seabed as part of a tsunami warning system. Solar power is commonly used to power up the electronic devices of these buoys. However, due to limitations in delivering constant power from solar panels, linear electric generators have been employed as an alternative/additional power source to convert the energy of oceanic waves into electricity. The variable AC amplitude and frequency of the generated voltage waveform is usually converted to DC using a simple, low cost diode bridge rectifier resulting in a low operating power factor (PF) and low power transfer capacity because of the high inductive reactance of linear electric generators. A Forced Commutation Controlled Series Capacitor (FCSC) technique is employed in this paper to improve the PF of these variable amplitude and very low and variable frequency devices. FCSC circuits have been employed in the past in power transmission networks where the voltage and frequency are fixed, but never in a wave power application where the amplitude and frequency of the AC voltage are variable. This paper provides an analytical description of the proposed FCSC converter. The method is experimentally demonstrated and evaluated using a 2.25kVA test circuit. A comparison of the performance of the FSCS circuit with a standard uncontrolled single-phase diode bridge rectifier circuit is included.

Impact of 2004 Tsunami in the Islands of Indian Ocean: Lessons Learned

Tsunami of 2004, caused by a 9.0 magnitude earthquake, is the most devastating tsunami in modern times, affecting 18 countries in Southeast Asia and Southern Africa, killing more than 250,000 people in a single day, and leaving more than 1.7 million homeless. However, less reported, albeit real, is its impact in the islands of the Indian Ocean more than 1,000 miles away from its epicenter. This is the first peer-reviewed paper on the 2004 tsunami events specifically in the eleven nations bordering the Indian Ocean, as they constitute a region at risk, due to the presence of tectonic interactive plate, absence of a tsunami warning system in the Indian Ocean, and lack established communication network providing timely information to that region. Our paper has a dual objective: the first objective is to report the 2004 tsunami event in relation to the 11 nations bordering the Indian Ocean. The second one is to elaborate on lessons learned from it from national, regional, and international disaster management programs to prevent such devastating consequences of tsunami from occurring again in the future.

Real-time earthquake monitoring for tsunami warning in the Indian Ocean and beyond

Abstract. The Mw = 9.3 Sumatra earthquake of 26 December 2004 generated a tsunami that affected the entire Indian Ocean region and caused approximately 230 000 fatalities. In the response to this tragedy the German government funded the German Indonesian Tsunami Early Warning System (GITEWS) Project. The task of the GEOFON group of GFZ Potsdam was to develop and implement the seismological component. In this paper we describe the concept of the GITEWS earthquake monitoring system and report on its present status. The major challenge for earthquake monitoring within a tsunami warning system is to deliver rapid information about location, depth, size and possibly other source parameters. This is particularly true for coast lines adjacent to the potential source areas such as the Sunda trench where these parameters are required within a few minutes after the event in order to be able to warn the population before the potential tsunami hits the neighbouring coastal areas. Therefore, the key for a seismic monitoring system with short warning times adequate for Indonesia is a dense real-time seismic network across Indonesia with densifications close to the Sunda trench. A substantial number of supplementary stations in other Indian Ocean rim countries are added to strengthen the teleseismic monitoring capabilities. The installation of the new GITEWS seismic network – consisting of 31 combined broadband and strong motion stations – out of these 21 stations in Indonesia – is almost completed. The real-time data collection is using a private VSAT communication system with hubs in Jakarta and Vienna. In addition, all available seismic real-time data from the other seismic networks in Indonesia and other Indian Ocean rim countries are acquired also directly by VSAT or by Internet at the Indonesian Tsunami Warning Centre in Jakarta and the resulting "virtual" network of more than 230 stations can jointly be used for seismic data processing. The seismological processing software as part of the GITEWS tsunami control centre is an enhanced version of the widely used SeisComP software and the well established GEOFON earthquake information system operated at GFZ in Potsdam (http://geofon.gfz-potsdam.de/db/eqinfo.php). This recently developed software package (SeisComP3) is reliable, fast and can provide fully automatic earthquake location and magnitude estimates. It uses innovative visualization tools, offers the possibility for manual correction and re-calculation, flexible configuration, support for distributed processing and data and parameter exchange with external monitoring systems. SeisComP3 is not only used for tsunami warning in Indonesia but also in most other Tsunami Warning Centres in the Indian Ocean and Euro-Med regions and in many seismic services worldwide.

The UNESCO-IOC framework – establishing an international early warning infrastructure in the Indian Ocean region

Abstract. The Sumatra-Andaman earthquake with a magnitude of 9.3, and the subsequent destructive tsunami which caused more than 225 000 fatalities in the region of the Indian Ocean, happened on 26 December 2004. Less than one month later, the United Nations (UN) World Conference on Disaster Reduction took place in Kobe, Japan to commemorate the 1995 Kobe earthquake. The importance of preparedness and awareness on regional, national and community levels with respect to natural disasters was discussed during this meeting, and resulted in the approval of the Hyogo Declaration on Disaster Reduction. Based on this declaration the UN mandated the Intergovernmental Oceanographic Commission (IOC) of UNESCO (United Nations Education, Science and Cultural Organization), taking note of its over 40 years of successful coordination of the Pacific Tsunami Warning System (PTWC), to take on the international coordination of national early-warning efforts for the Indian Ocean and to guide the process of setting up a Regional Tsunami Early Warning System for the Indian Ocean.

Tsunami Forecasting and Monitoring in New Zealand

New Zealand is exposed to tsunami threats from several sources that vary significantly in their potential impact and travel time. One route for reducing the risk from these tsunami sources is to provide advance warning based on forecasting and monitoring of events in progress. In this paper the National Tsunami Warning System framework, including the responsibilities of key organisations and the procedures that they follow in the event of a tsunami threatening New Zealand, are summarised. A method for forecasting threat-levels based on tsunami models is presented, similar in many respects to that developed for Australia by Allen and Greenslade (Nat Hazards 46:35–52, 2008), and a simple system for easy access to the threat-level forecasts using a clickable pdf file is presented. Once a tsunami enters or initiates within New Zealand waters, its progress and evolution can be monitored in real-time using a newly established network of online tsunami gauge sensors placed at strategic locations around the New Zealand coasts and offshore islands. Information from these gauges can be used to validate and revise forecasts, and assist in making the all-clear decision.

Managing tsunamis through early warning systems: A multidisciplinary approach

This study attempts to identify the key factors that will make a tsunami warning system most effective, to develop a framework in which results of natural science and engineering research can be effectively integrated into coastal natural hazard planning, and to develop a numerical example that illustrates how benefit-cost analysis may be used to assess early warning systems. Results of the study suggest that while the science of tsunami wave propagation and inundation is relatively advanced, our knowledge on the relationships between tsunami generation and undersea earthquakes, volcanic eruptions, and landslides remains poor, resulting in significant uncertainties in tsunami forecasting. Probabilities of damaging tsunamis for many coastal regions are still unknown, making tsunami risk assessment and management difficult. Thus it is essential to develop new techniques to identify paleo-tsunami events and to compile and develop size and frequency information on historical tsunamis for different locations. An effective tsunami early warning system must include not only the ocean technologies for accurately detecting an emerging tsunami, but also a civil communication system through which the population can be timely warned by the local government and other sources. Since minimizing the evacuation time is a key factor to make a warning system effective, adequate pre-event education and preparation of the population must be a critical component of the system. Results of a numerical example of the South Pacific region suggest that investments in a tsunami warning system in the region may lead to significant economic benefits.

Research for disaster preparedness

Research for disaster preparedness

Source modeling and inversion with near real-time GPS: a GITEWS perspective for Indonesia

Abstract. We present the GITEWS approach to source modeling for the tsunami early warning in Indonesia. Near-field tsunami implies special requirements to both warning time and details of source characterization. To meet these requirements, we employ geophysical and geological information to predefine a maximum number of rupture parameters. We discretize the tsunamigenic Sunda plate interface into an ordered grid of patches (150×25) and employ the concept of Green's functions for forward and inverse rupture modeling. Rupture Generator, a forward modeling tool, additionally employs different scaling laws and slip shape functions to construct physically reasonable source models using basic seismic information only (magnitude and epicenter location). GITEWS runs a library of semi- and fully-synthetic scenarios to be extensively employed by system testing as well as by warning center personnel teaching and training. Near real-time GPS observations are a very valuable complement to the local tsunami warning system. Their inversion provides quick (within a few minutes on an event) estimation of the earthquake magnitude, rupture position and, in case of sufficient station coverage, details of slip distribution.

Numerical Modeling of Generation and Propagation of Tsunami Waves along the Southern Coast of Iran

The main goal of this study is to increase the software capabilities of Iran towards the development of a tsunami warning system for its southern coast bordering the Indian Ocean. The devastating tsunami of 26 December 2004 in the Indian Ocean region emphasized the necessity for development of tsunami warning systems for the world’s vulnerable coastlines, especially for those neighboring the Indian Ocean. Studies showed that there are two main tsunamigenic zones in the Indian Ocean region, namely the Sumatra subduction zone in the east and the Makran subduction zone at the northwest of this ocean. The Makran subduction zone is located offshore Iran and Pakistan and produced some destructive tsunamis in the past. The most recent tsunami in the Makran region occurred on 28 November 1945 which claimed more than 4000 lives along the coasts of Iran, Pakistan, Oman and India. As the southern coast of Iran is at risk of tsunami from the Makran subduction zone, Iran is committed to work towards the development of a tsunami warning system, and to cooperate with the countries in the region in this field. All activities towards the development of a tsunami warning system can be classified into two categories: 1) hardwares like tsunameters, tide gauges, seismic networks, and etc., and 2) softwares. Numerical modeling of tsunami is among the second group and is a vital part of any tsunami warning system. Here, we discuss the modeling of tsunami generation and propagation. At first, the algorithm for tsunami generation modeling is presented and then, the generation phase of a possible tsunami in the region was modeled. The results of generation modeling were compared with international experiences. In the next section, the propagation of tsunami was modeled using a well-validated international numerical model for long waves. Results of the tsunami generation modeling showed that in the case of an earthquake with a moment magnitude of 8, the maximum vertical uplift of the seafloor will be about 1.5 m, and an area with the dimensions of 150 and 250 km will be deformed due to the earthquake. Tsunami propagation modeling showed that the first tsunami waves will hit the nearest coastline within 15-20 min after the earthquake. The maximum tsunami wave height was estimated about 3 m. It is showed that how the results of the numerical modeling of tsunami can help to develop a tsunami warning system. Our preliminary investigation shows that at least 891 case-scenarios should be simulated to develop the tsunami warning system in the Makran region.

Concept for developing a seismologic observation system for tsunami warning in the Russian Far East

The initial information and requirements for developing a seismologic observation system and data-processing and transfer tools for a tsunami warning system and its functions and tasks are considered. The structure of the seismologic observation system for the tsunami warning service (TWS) in the Russian Far East is proposed. A study of general technical and methodological problems is carried out to increase the efficiency for urgent tsunami prediction from continuous seismic monitoring data of territories of the Russian Far East and the world. Special attention is paid to the problem of tsunami prediction from seismologic data on strong earthquakes in near zone of a protected territory (up to 200 km).